Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 114)

98 Dolby ® DP570 Multichannel Audio Tool User’s Manual
A Guide to Dolby Metadata
Original Bitstream
This parameter indicates whether the encoded Dolby Digital bitstream is the master
version or a copy. It has no effect on Dolby Digital decoders and its purpose is purely to
provide information.
Figure D‐4
DC Filter
This parameter determines whether a DC‐blocking 3 Hz highpass filter is applied to the
main input channels of a Dolby Digital encoder prior to encoding. This parameter is not
carried to the consumer decoder. It is used to remove DC offsets in the program audio and
would only be switched off in exceptional circumstances.
Lowpass Filter
This parameter determines whether a lowpass filter is applied to the main input channels
of a Dolby Digital encoder prior to encoding. This filter removes high‐frequency signals
that are not encoded. At the suitable data rates, this filter operates above 20 kHz. In all cases
it prevents aliasing on decoding and is normally switched on. This parameter is not passed
to the consumer decoder.
LFE Lowpass Filter
This parameter determines whether a 120 Hz eighth‐order lowpass filter is applied to the
LFE channel input of a Dolby Digital encoder prior to encoding. It is ignored if the LFE
channel is disabled. This parameter is not sent to the consumer decoder. The filter removes
Table D-15 Original Bitstream Settings
Original Bitstream
Yes
No
Note: The parameters DC Filter, Lowpass Filter, LFE Lowpass Filter, Surround 3 dB
Attenuation, and Surround Phase Shift appear after the Extended BSI parameters on
Dolby E and Dolby Digital equipment menus.
Table D-16 DC Filter Settings
DC Filter
Enabled
Disabled
Table D-17 Lowpass Filter Settings
Lowpass Filter
Enabled
Disabled